staging/lustre/obdclass: add empty tailing member to ctl_table

This was mistakenly removed by commit 7fb3d1c5.
Now register_sysctl_table() complains about "No proc_handler".

Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: NPeng Tao <bergwolf@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/linux/linux-sysctl.c

@@ -392,7 +392,8 @@ static ctl_table_t obd_table[] = {
 		.maxlen   = sizeof(int),
 		.mode     = 0644,
 		.proc_handler = &proc_at_history
-	}
+	},
+	{}
 };
 
 static ctl_table_t parent_table[] = {
@@ -402,7 +403,8 @@ static ctl_table_t parent_table[] = {
 		.maxlen   = 0,
 		.mode     = 0555,
 		.child    = obd_table
-	}
+	},
+	{}
 };
 #endif